Well-casing centralizers



Nov. 6, 1962 R. TYRRELL, JR 3,062,297

WELL-CASING CENTRALIZERS Filed Nov. 25. 1960 FIG. I

INVENTOR. ROBERT TYRRELL, JR.

FIG. 4 BY i ATTORNEY United States Patent 3,062,297 WELL-CASING EENTRALIZERS Robert Tyrrell, Jr., 2124 Carey Place, Oklahoma City, Okla.

Filed Nov. 25, 150, Ser. No. 71,737 9 Claims. (Cl. 166-241) This invention relates in general to certain new and useful improvements in oil well drilling devices and, more particularly, to well-casing centralizers.

In the drilling of oil Wells, it is conventional practice to drill the well-bore or socalled hole into the ground by means of a rotary drill. The well-bore will be drilled to some selected diametral size and a casing of somewhat smaller diametral size will be set into the well-bore in such a manner that there is an annular space between the side walls of the well-bore and the outer surfaces of the casing. While the well is being drilled, the space between the drill and wall of the well-bore is used for the upward circulation and removal of well drilling mud which is pumped down into the well through the internal bore of the. rotary drill and serves the dual purpose of facilitating the cutting action of the drill-bit and removing the disintegratingrock,shale, and earth which is cut away by the bit. When the drilling action'has been completed, the casing is thereupon inserted and cemented permanently in the well-bore by pumping fluid cement down through the casing and forcing it upwardly into the annular space between the outer surfaces of the casing and the side walls of the well-bore.

The drilling mud which is circulated through the wellbore during the drilling operation ordinarily leaves a coating of deposited solids which will interfere with the cementing operation. Therefore, the casing is usually equipped at suitably spaced sections throughout its length with radially projecting devices referred to as scratchers. These scratchers will extend outwardly across the annular space between the outer surfaces of the casing and the side walls of the well-bore and will scratch away the accumulated deposits left by the drilling mud when the casing is rotated in place. It is, of course, also necessary that the casing be located as nearly as possible in concentric position within the well-bore. In other words, the longitudinal axis of the casing should be substantially coincident with the longitudinal axis of the well-bore and, when the casing is in this proper location, it is referred to as being centralized. In order to achieve this centralized position, the well-casing is equipped with ex-- ternally projecting, somewhat resilient devices or so-called centralizers which contact the side walls of the wellbore and hold the casing in centralized position therein. Devices of this type which are presently in use, however, tend to bind both against the casing and the well-bore, thereby setting up frictional forces which impede and often prevent rotation of the casing when it is desired to bring the scratchers into operation for cleaning away the deposit left by the drilling mud.

It is, therefore, the primary object of the present invention to provide a well-casing centralizer which is capable of centralizing the well-casing within the well-bore while at the same time affording freedom for rotation of the casing preparatory to cementing operations.

It is another object of the present invention to provide a well-casing centralizer of the type stated which can be easily and conveniently installed upon the casing and will be held firmly thereon against unauthorized axial shifting movement with respect to the casing.

It is a further object of the present invention to provide a well-casing centralizer of the type stated which is simple and economical in construction, but is nevertheless, rugged, durable, and capable in withstanding the sub- 3,062,297 Patented Nov. 6, 1962 stantial stresses and strains encountered under conditions to actual use.

With the above and other objects in view, my invention resides in the novel features of form, construction, arrangement, and combination of parts presently described and pointed out in the claims.

In the accompanying drawing (one sheet) FIG. 1 is a fragmentary sectional view of a well-bore and casing equipped with a well-casing centralizer constructed in accordance with and embodying the present invention;

FIG. 2 is an elevational view of a well-casing centralizer constructed in accordance with and embodying the present invention;

FIG. 3 is a transverse sectional view taken along line 3-3 of FIG. 2;

FIG. 4 is a fragmentary sectional view taken along line 4-4 of FIG. 3;

FIG. 5 is a fragmentary elevational view of a modified form of well-casing centralizer constructed in accordance with and embodying the present invention; and

FIG. 6 is a transverse sectional view taken along line 66 of FIG. 5.

Referring now in more detail and by reference characters to the drawing, which illustrates practical embodiments of the present invention, A designates a well-bore drilled into the ground in any conventional manner and provided with a string of casing B. It will, of course, be understood that the well-bore A and string of casing B may be of any suitable length or diametral size and, moreover, that the string of casing will consist of a plurality of joints which are threadedly interconnected.

Provided for disposition around the otuside surface of the casing B is a well-casing centralizer C including a pair of axially spaced cylindrical collars or bands 1, 2, having an internal diametral size adapted for loose-fitting or annularly spaced disposition around the casing B. Welded or otherwise rigidly secured at their upper ends to the upper collar 1 are four equally spaced axially extending flat bars 3 formed of spring steel stock and being curved or bowed outwardly for resilient contact along their central portions with side walls of the well-bore A. At the lower ends, the bars 3 are welded to the lower collar or band 2, thereby holding the collar or bands 1, 2, in axially spaced relation, as best seen in FIG. 2.

It should be noted in this connection that the wellcasing centralizer C is shown and herein described as having four resilient bars 3, but it should be understood that a different number of bars may be employed so long as the bars are symmetrically placed in relation to each other.

The upper collar or band 1 is provided, intermediate each pair of adjacent bars 3, with a rectangular aperture 4 bordered across its top and bottom transverse margins with upstruck strap portions 5, 6, in the provision of retainer sockets for engagement with the upper and lower ends, respectively, of a pin-like vertical shaft 7. Rotatably mounted upon each of the pin-like shafts 7 is a roller bearing 8 held in place between pairs of set collars 9, 10, the latter being secured to the pin-like shaft 7 by means of set screws 11, 12, respectively. The roller hearing 8 is turned down at its outer ends in the provision of annular arcuate shoulders 13, 14, and a flat diametrally enlarged central or crowned bearing surface 15, the latter being of such diametral size as to extend throughthe aperture 4 and bear roller-wise against the outer surface 0 the casing B, as best seen in FIG. 3.

The well-casing centralizer C is held in place against axial shifting movement against the casing by means of cylindrical clamping collars 16, 17, whichare rigidly affixed to the casing B by means ofa' plurality of set 3 screws 18, 19, respectively. As shown in FIG. 1, the collar 16 is disposed in endwise abutment against the upper margin of the band 1 and the collar 17 is disposed in endwise abutment against the lower margin of the band 2. The tightness of abutment between the collars 16, 17, and the bands 1, 2, is just sufiicient to hold the well-casing centralizer C in position on the casing B, but will not bind the well-casing centralizer C or prevent relative rotation between the centralizer C and the casing B as facilitated by the rollers 8.

The well-casing centralizer C is installed upon each joint of casing B before it is connected in the string simply by slipping the band 2 over the free end of the joint of easing B and sliding it along to a desired position. At the same time, a clamping collar 16 is slipped over the end of the joint of easing B and pushed along with the wellcasing centralizer C in the relative position shown in PEG. 1. When the clamping collar 16 and the wellcasing centralizer C are located in the desired position along the casing B, the set screws 17, 18, are tightened down, thereby locking the clamping collar 16 in place. Thereupon, such particular joint of casing B can be spun into the next adjacent joint of casing and lowered into the well-bore A.

If desired, it is possible to provide a modified form of well-casing centralizer C which is substantially identical in all respects with the previously described well-casing centralizer C, except that, instead of collars or bands, such as the previously described collars or bands 1, 2, it is provided with a form of split collar 1' composed of two semi-circular sections 20, 21, which fit together in edgewise relation to form a cylindrical casing-encircling element. The sections 20, 21, are respectively provided with axially aligned internesting sets of hinge eyes 22, 23, 24, which extend across the lines of axial abutment between the sections 20, 21, and receive drive pins 25. The wellcasing centralizer C can be applied to the casing B by removal of the drive pins 25, so that the two separated halves thereof can be fitted together around the well-casing, whereupon the drive pins 25 may be inserted to hold the sections in encircling relationship around the casing B.

It should be understood that changes and modifications in the form, construction, arrangement, and combination of the several parts of the oil well drilling devices may be made and substituted for those herein shown and described without departing from the nature and principle of my invention.

Having thus described my invention, what I claim and desire to secure by Letters Patent is 1. A well casing centralizer comprising two axially spaced collars connected by a plurality of symmetrically positioned axially extending bands, said collars being provided with upstruck strap portions and rectangular apertures at each of their transverse margins, an axially extending shaft mounted in each of said apertures, bearing elements mounted on said shaft and projecting inwardly for engagement with the casing whereby to support the centralizer in annularly spaced rotatable relation around the casing.

2. A well casing centralizer comprising two axially spaced collars connected by a plurality of symmetrically positioned axially extending bands, said collars being provided with upstruck strap portions and rectangular apertures at each of their transverse margins, an axially extending shaft mounted in each of said apertures, roller bearing elements mounted on said shaft and projecting inwardly for engagement with the casing whereby to support the centralizer in annularly spaced rotatable relation around the casing.

3. A well casing centralizer comprising two axially spaced collars connected by a plurality of symmetrically positioned axially extending bands, said collars being provided with upstruck strap portions and rectangular apertures at each of their transverse margins, an axially extending shaft mounted in each of said apertures, axially extending roller bearing elements mounted on said shaft and projecting inwardly for engagement with the casing whereby to support the centralizer in annularly spaced rotatable relation around the casing.

4. A well casing centralizer comprising two axially spaced collars connected by a plurality of symmetrically positioned axially extending resilient bands, said collars being provided with upstruck strap portions and rectangular apertures at each of their transverse margins, an axially extending shaft mounted in each of said apertures, bearing elements mounted on said shaft and projecting inwardly for engagement with the casing whereby to support the centralizer in annularly spaced rotatable relation around the casing.

5. A well casing centralizer comprising two axially spaced collars connected by a plurality of symmetrically positioned axially extending bands, said collars being provided with upstruck strap portions and rectangular apertures at each of their transverse margins in the provision of retainer sockets, an axially extending shaft mounted in each of said sockets, centrally crowned roller bearing elements mounted on said shaft and projecting inwardly for engagement with the casing whereby to support the centralizer in annularly spaced rotatable relation around the casing, said bearing elements having a crowned bearing surface that is diametrally reduced at each end in the provision of annular arcuate shoulders.

6. A well casing centralizer comprising two axially spaced collars connected by a plurality of symmetrically positioned axially extending bands, said collars being provided with upstruck strap portions and rectangular apertures at each of their transverse margins in the provision of retainer sockets, an axially extending shaft mounted in each of said sockets, bearing elements mounted on said shaft and projecting inwardly for engagement with the casing whereby to support the centralizer in annularly spaced rotatable relation around the casing, said bearing elements having a crowned bearing surface that is diametrally reduced at each end in the provision of annular arcuate shoulders, said collars being axially split and provided with internested aligned eye-forming elements releasably secured together by pins.

7. A well casing centralizer comprising two axially spaced collars connected by a plurality of symmetrically positioned axially extending bands, said collars being provided with upstruck strap portions and rectangular apertures at each of their transverse margins in the provision of retainer sockets, an axially extending shaft mounted in each of said sockets, bearing elements mounted on said shaft and projecting inwardly for engagement with the casing whereby to support the centralizer in annularly spaced rotatable relation around the casing, said bearing elements having a crowned bearing surface that is diametrally reduced at each end in the provision of annular arcuate shoulders, said collars being axially split and provided with internested aligned eye-forming elements releasably secured together by tapered pins.

8. A well casing centralizer comprising two axially spaced collars connected by a plurality of symmetrically positioned axially extending resilient bands, said collars being provided with upstruck strap portions and rectangular apertures at each of their transverse margins in the provision of retainer sockets, an axially extending shaft mounted in each of said sockets, roller bearing elements mounted on said shaft and projecting inwardly for engagement with the casing whereby to support the centralizer in annularly spaced rotatable relation around the casing, said bearing elements having a crowned bearing surface that is diametrally reduced at each end in the provision of annular arcuate shoulders.

9. A well casing centralizer comprising two axially spaced collars connected by a plurality of symmetrically positioned axially extending resilient bands, said collars being provided with upstruck strap portions and rectangulat apertures at each of their transverse margins in the provision of retainer sockets, an axially extending shaft mounted in each of said sockets, axially extending roller bearing elements mounted on said shaft and projecting inwardly for engagement with the casing whereby to support the centralizer in annularly spaced rotatable relation around the casing, said bearing elements having a crowned bearing surface that is diametrally reduced at each end in the provision of annular arcuate shoulders.

References Cited in the file of this patent UNITED STATES PATENTS Vaughn Dec. 22, 1925 Santiago Dec. 13, 1932 Smith Apr. 16, 1940 Hartman et al July 21, 1942 Pyle et a1 Feb. 12, 1957 Baker May 30, 1961 

